The bearing type most commonly used as a fixed bearing for the mounting of the main shaft in a motor vehicle transmission is the single-row deep-groove ball bearing, because this is distinguished by uniformly high radial and axial load capacities and has the highest rotational speed limits of all bearing types owing to its low friction. Said deep-groove ball bearing is, in a known manner, composed of an outer bearing ring and of an inner bearing ring and of a multiplicity of bearing balls arranged between the bearing rings, which bearing balls roll in groove-like raceways formed into the inner side of the outer bearing ring and into the outer side of the inner bearing ring and are guided with uniform spacings to one another by means of a bearing cage. Here, the insertion of the bearing balls into the deep-groove ball bearing is normally performed using the eccentric assembly method that has become known from DE 168 499 A1, in which the two bearing rings are arranged eccentrically with respect to one another, the free space thus formed between the bearing rings is filled with the bearing balls, the bearing rings are subsequently moved into a concentric position with respect to one another utilizing their elasticity, and the bearing cage is inserted after the bearing balls have been uniformly circumferentially distributed.
In practice, however, it has been found that such deep-groove ball bearings, owing to the small maximum number of bearing balls that can be installed, which number is dependent on the dimensions of the inner and of the outer bearing ring and on the diameter of the bearing balls, are always subject to certain limits in particular with regard to the radial load capacity of the bearing. In the past, therefore, a multiplicity of solutions has been proposed, such as for example a non-closed filling opening arranged in the oppositely situated rims of the raceway of the outer and of the inner bearing ring, as per DE 151 483 A1, or a similarly designed closable filling opening, as per DE 24 07 477 A1, by means of which it has been sought to achieve an increase in the radial load capacity of deep-groove ball bearings through an increase in the number of bearing balls, though said solutions have not been able to become established in practice owing to the disadvantages resulting from such filling openings.
Another possibility for increasing the load capacity of the fixed bearing for the mounting of the main shaft in a motor vehicle transmission would be to replace the previously used deep-groove ball bearing with a cylindrical roller bearing of the type NUP, such as is known for example from the applicant's catalogue “Walzlager” [“Rolling bearings”], dated October 2008, on pages 393 and 396. Said cylindrical roller bearing has two lateral rims both on the inner bearing ring and on the outer bearing ring, and is suitable for accommodating high radial loads and axial loads in both directions. Such cylindrical roller bearings however have very high manufacturing costs owing to the high level of cutting machining, in particular for the raceway production and for the rim machining, and would furthermore in turn be overdimensioned in terms of their load capacity, such that they are ultimately unsuitable for use as fixed bearings in motor vehicle manual transmissions.
A further bearing type which is suitable as a fixed bearing for the mounting of the main shaft in a motor vehicle transmission and which forms the closest prior art for the present disclosure and whose capacity for accommodating radial forces and axial forces in both directions is greater than that of deep-groove ball bearings has become known from the documents DE 6 917 609 U and CH 463 886 A. Said documents each disclose an angular contact roller bearing which is composed substantially of an inner bearing ring with an inner raceway, which is arranged on the outer shell surface of said inner bearing ring obliquely with respect to the radial bearing axis, and of a rim which delimits said raceway at its smallest diameter, of an outer bearing ring with outer raceway, which is arranged on the inner shell surface of said outer bearing ring, likewise obliquely with respect to the radial bearing axis, and of a rim which delimits said raceway at its greatest diameter, and of a multiplicity of roller-type rolling bodies which are arranged between the bearing rings and which roll on the raceways of said bearing rings and which are held with uniform spacings to one another in a circumferential direction by means of a bearing cage. To permit the insertion of the rolling bodies in the form of tapered rollers into the bearing cage which is formed in each case as a pocket-type or window-type cage, it is the case that the rim on the inner bearing ring in the case of the angular contact roller bearing as per DE 6 917 609 U, and the rim on the outer bearing ring in the case of the angular contact roller bearing as per CH 463 886 A, is formed as a separate component which is fastened to the inner or outer bearing ring respectively after the bearing assembly process. This is performed, in the case of the angular contact roller bearing as per DE 6 917 609 U, through a separate slotted ring which is U-shaped in cross section and the radial limbs of which engage in to corresponding grooves in the rim and in the inner bearing ring, and in the case of the angular contact roller bearing as per CH 463 886 A, through an encircling collar integrally formed on the underside of the rim, which collar is pressed into the outer bearing ring.
In such angular contact roller bearings, although the fact that only one of the bearing rings is formed integrally with only one lateral rim has the effect that the level of cutting machining during the raceway production and during the rim machining, and thus also the overall costs for the bearing manufacture, are much lower than in the case of the cylindrical roller bearing described above, it is nevertheless the case in such angular contact roller bearings that the formation of the rim on the respective other bearing ring as a separate rim disk, the additional installation thereof on said bearing ring and the required precision manufacture of the contact surfaces on said rim disk and on the associated bearing ring have an adverse effect on the production costs thereof. Furthermore, in the case of such angular contact roller bearings, there is the risk that the fastening of the separate rim disk is not sufficient to withstand even high radial or axial load peaks, such that the rim disk can become detached during bearing operation, ultimately resulting in bearing failure.